Moxa MGate Protocol Gateways

1. EXECUTIVE SUMMARY

• CVSS v3 9.8
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Moxa
• Equipment: MGate MB3180/MB3280/MB3480 Series Protocol Gateways
• Vulnerability: Cleartext Transmission of Sensitive Information

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow remote attackers to obtain sensitive information.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following firmware versions of MGate MB3000 Series, a serial-to-Ethernet Modbus gateway, are affected:

• MGate MB3180 Series: Firmware Version 2.2 or lower
• MGate MB3280 Series: Firmware Version 4.1 or lower
• MGate MB3480 Series: Firmware Version 3.2 or lower

3.2 VULNERABILITY OVERVIEW

3.2.1    CLEARTEXT TRANSMISSION OF SENSITIVE INFORMATION CWE-319

The affected products contain vulnerable firmware, which could allow an attacker to sniff the traffic and decrypt login credential details. This could give an attacker admin rights through the HTTP web server.

CVE-2021-4161 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Multiple Sectors
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Taiwan

3.4 RESEARCHER

Parul Sindhwad, Anurag M. Chevendra, and Dr. Faruk Kazi of CoE-CNDS Lab; VJTI; and Mumbai-INDIA reported this vulnerability to Moxa.

4. MITIGATIONS

Moxa has developed the following mitigations to address this vulnerability.

• Enable ‘HTTPS’ and disable the HTTP console function under ‘Console Settings’

Moxa also recommends users refer to Tech Note: Moxa Security Hardening Guide for MGate MB3000 Series

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:

• Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the Internet.
• Locate control system networks and remote devices behind firewalls and isolate them from the business network.
• When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its connected devices.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.



CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage on cisa.gov in the Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.



Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to CISA for tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability.